另一种想法的方法是我想做Array.prototype.join( arr.join(sep) ),而没有结果是一个字符串(因为我想要使用的元素和分隔符是对象,而不是字符串)。
是否有功能/漂亮/优雅的方式来做这个在es6 / 7或lodash没有任何感觉笨拙的东西像:
_。 (arr.map((el,i)=> [el,i< arr.length-1?sep:null]))//太复杂或
_。flatten(arr.map(el => ; [el,sep])。slice(0,-1)// extra sep added,memory wasted甚至
arr.reduce((prev,curr)=> {prev.push(curr,sep);返回上一个;},[])。slice(0,-1) //可能是三个中最好的,但是我必须做一个地图已经 //,我还是一样问题如前两个 - //内联三元或片编辑:Haskell具有此功能,称为 intersperse
解决方案使用生成器:
function * intersperse(a,delim){ let first = true ; for(const x of a){ if(!first)yield delim; first = false; yield x; } } console.log([... intersperse(array,'&')]);感谢@Bergi指出有用的泛化,输入可以是任何可迭代的。 >
如果你不喜欢使用生成器,那么
[]。 (... a.map(e => ['&',e]))slice(1)
Say I have an array var arr = [1, 2, 3], and I want to separate each element by an element eg. var sep = "&", so the output is [1, "&", 2, "&", 3].
Another way to think about it is I want to do Array.prototype.join (arr.join(sep)) without the result being a string (because the elements and separator I am trying to use are Objects, not strings).
Is there a functional/nice/elegant way to do this in either es6/7 or lodash without something that feels clunky like:
_.flatten(arr.map((el, i) => [el, i < arr.length-1 ? sep : null])) // too complexor
_.flatten(arr.map(el => [el, sep]).slice(0,-1) // extra sep added, memory wastedor even
arr.reduce((prev,curr) => { prev.push(curr, sep); return prev; }, []).slice(0,-1) // probably the best out of the three, but I have to do a map already // and I still have the same problem as the previous two - either // inline ternary or sliceEdit: Haskell has this function, called intersperse
解决方案Using a generator:
function *intersperse(a, delim) { let first = true; for (const x of a) { if (!first) yield delim; first = false; yield x; } } console.log([...intersperse(array, '&')]);Thanks to @Bergi for pointing out the useful generalization that the input could be any iterable.
If you don't like using generators, then
[].concat(...a.map(e => ['&', e])).slice(1)
更多推荐
简单的方式来插入JavaScript数组中所有元素之间的元素?
发布评论